Should I post an answer with a link to this question? If I do, it gets converted automatically to a comment.

Normally, we would discourage short answers with just a link. However, considering that the link is pointing to another Stack Exchange website, where answers can be edited and voted on, surely it's OK?

I can't flag the question as a duplicate, because the duplicate isn't on Ask Ubuntu.

2 Answers
2

Answer as you normally would (with the "full" answer text), use the U&L as source.

Just linking to it negates the use of the question as a Q&A article and thus is discouraged - even in this scenario. Stick to comments if you don't want to create a dupe, answer "properly" if you want it as an actual answer.

Not really. :P
Basically, you need to answer their question, then cite the source. The important thing is that your answer needs to answer their question. Citing sources is recommended (1, it's a good practice; and 2, the user might need more detail than you provided,) but, when answering their question, answer their question.

If you see a link-only answer, then you basically have 2 options:

Downvote theirs, and post your own answer. (If you don't know anything about the question, look at the link that was posted. Then, you can sound like an expert while actually previously knowing nothing and gaining from the very answer that you downvoted. >:)